R. J. Garcı́a López
A5105509956- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Astronomical Observations and Instrumentation
- Particle Accelerators and Free-Electron Lasers
- Particle physics theoretical and experimental studies
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Atmospheric Ozone and Climate
- Scientific Research and Discoveries
- Radiation Detection and Scintillator Technologies
- Radiation Therapy and Dosimetry
- Atomic and Molecular Physics
- Noncommutative and Quantum Gravity Theories
- Atomic and Subatomic Physics Research
Universidad de La Laguna
2016-2025
Instituto de Astrofísica de Canarias
2016-2025
Universitat de Barcelona
2002-2024
Institut d'Estudis Espacials de Catalunya
2024
Foundation for Research and Technology Hellas
2023
University of Siena
2023
Boston University
2023
MAGIC Telescopes
2022
University of Trieste
2021
Max Planck Institute for Physics
2021
A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge dependence important understanding origin, acceleration, and propagation rays. We present detailed variation spectral index for first time. The progressively hardens at high rigidities.Received 6 March 2015DOI:https://doi.org/10.1103/PhysRevLett.114.171103This article available under terms Creative Commons Attribution 3.0...
Measurements of the positron fraction in high energy cosmic rays using space-borne Alpha Magnetic Spectrometer have been extended to energies 500 GeV. The new results show that stops increasing with at around 200
Precision measurements by the Alpha Magnetic Spectrometer on International Space Station of primary cosmic-ray electron flux in range 0.5 to 700 GeV and positron 500 are presented. The each require a description beyond single power-law spectrum. Both change their behavior at ∼30 but fluxes significantly different magnitude energy dependence. Between 20 200 spectral index is harder than index. determination differing indices versus new observation provides important information origins...
The blazar Mrk 501 was observed at energies above 0.10 TeV with the MAGIC Telescope from 2005 May through July. high sensitivity of instrument enabled determination flux and spectrum source on a night-by-night basis. Throughout our observational campaign, found to vary by an order magnitude. Intranight variability flux-doubling times down 2 minutes during two most active nights, namely, June 30 July 9. These are fastest variations ever in 501. ~20 minute long flare 9 showed indication 4 ± 1...
Knowledge of the precise rigidity dependence helium flux is important in understanding origin, acceleration, and propagation cosmic rays. A measurement primary rays with (momentum/charge) from 1.9 GV to 3 TV based on 50 million events presented compared proton flux. The detailed variation spectral index for first time. progressively hardens at rigidities larger than 100 GV. similar that though magnitudes are different. Remarkably, ratio increases up 45 then becomes constant; above well...
A precision measurement by AMS of the antiproton flux and antiproton-to-proton ratio in primary cosmic rays absolute rigidity range from 1 to 450 GV is presented based on 3.49×10^{5} events 2.42×10^{9} proton events. The fluxes ratios charged elementary particles are also presented. In ∼60 ∼500 GV, p[over ¯], p, positron e^{+} found have nearly identical dependence electron e^{-} exhibits a different dependence. Below 60 (p[over ¯]/p), ¯]/e^{+}), (p/e^{+}) each reaches maximum. From show no...
We present the first joint analysis of gamma-ray data from MAGIC Cherenkov telescopes and Fermi Large Area Telescope (LAT) to search for signals dark matter annihilation in dwarf satellite galaxies. combine 158 hours Segue 1 observations with 6-year 15 galaxies by -LAT. obtain limits on cross-section particle masses between 10 GeV 100 TeV—the widest mass range ever explored a single analysis. These improve previously published -LAT results up factor two at certain masses. Our new inclusive...
Very high energy (VHE) γ-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35, z = 0.432) was detected with MAGIC Cherenkov telescopes during a short observation (∼0.5 hr) performed on 2010 June 17. The detection coincides high-energy MeV/GeV activity measured by Large Area Telescope (LAT) board Fermi satellite. VHE extends about 70 GeV up to at least 400 and can be well described power-law dN/dE ∝ E−Γ photon index Γ 3.75 ± 0.27stat 0.2syst. averaged integral flux...
The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector on the International Space Station (ISS) conducting unique, long-duration mission of fundamental research in space. objectives include precise studies origin dark matter, antimatter, and cosmic rays as well exploration new phenomena. Following 16-year period construction testing, precursor flight Shuttle, AMS was installed ISS May 19, 2011. In this report we present results based 120 billion charged ray events up...
Knowledge of the rigidity dependence boron to carbon flux ratio (B/C) is important in understanding propagation cosmic rays. The precise measurement B/C from 1.9 GV 2.6 TV, based on 2.3 million and 8.3 nuclei collected by AMS during first 5 years operation, presented. detailed variation with spectral index reported for time. does not show any significant structures contrast many ray models that require such at high rigidities. Remarkably, above 65 GV, well described a single power law R^{Δ}...
We report about very high energy (VHE) γ-ray observations of the Crab Nebula with MAGIC telescope. The flux from nebula was measured between 60 GeV and 9 TeV. spectrum can be described by a curved power law dF/dE = f0(E/300 GeV)[a+blog10(E/300 GeV)] normalization f0 (6.0 ± 0.2stat) × 10−10 cm−2 s−1 TeV−1, − 2.31 0.06stat, b 0.26 0.07stat. peak in spectral distribution is estimated at 77 35 GeV. Within observation time experimental resolution telescope, emission steady pointlike. emission's...
We report the observation of new properties primary cosmic rays He, C, and O measured in rigidity (momentum/charge) range 2 GV to 3 TV with 90×10^{6} helium, 8.4×10^{6} carbon, 7.0×10^{6} oxygen nuclei collected by Alpha Magnetic Spectrometer (AMS) during first five years operation. Above 60 GV, these three spectra have identical dependence. They all deviate from a single power law above 200 harden an way.
We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in range 0.5 GeV to 1 TeV based on analysis 10.6 million events collected by AMS. The statistics and resolution AMS provide precision flux. is smooth reveals new distinct information. Above 30.2 GeV, can be described single power law with spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).
Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million collected by the Alpha Magnetic Spectrometer International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties (a) a significant excess starting from 25.2±1.8 GeV compared lower-energy, power-law trend, (b) sharp dropoff above 284+91−64 GeV, (c) in entire range is well described sum term associated with produced collision rays, which dominates at low...
We report on the observation of new properties secondary cosmic rays Li, Be, and B measured in rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total 5.4×10^{6} nuclei collected by AMS during first five years operation aboard International Space Station. The Li fluxes have an identical dependence above 7 all three 30 Li/Be flux ratio 2.0±0.1. deviate from single power law 200 way. This behavior has also been observed measurement primary He, C, O but dependences are...
Abstract A neutrino with energy ∼290 TeV, IceCube-170922A, was detected in coincidence the BL Lac object TXS 0506+056 during enhanced gamma-ray activity, chance being rejected at ∼3 σ level. We monitored very-high-energy (VHE) band Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for ∼41 hr from 1.3 to 40.4 days after detection. Day-timescale variability is clearly resolved. interpret quasi-simultaneous and broadband electromagnetic observations a novel one-zone...
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based $28.1\ifmmode\times\else\texttimes\fi{}{10}^{6}$ collected by Alpha Magnetic Spectrometer International Space Station. In entire electron and positron spectra have distinctly different magnitudes dependences. The flux exhibits a significant excess starting $42.{1}_{\ensuremath{-}5.2}^{+5.4}\text{ }\text{ }\mathrm{GeV}$ compared lower trends, but nature of this is above...
We present results over an 11-year Solar cycle of cosmic antiprotons based on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>1.1</a:mn><a:mo>×</a:mo><a:msup><a:mn>10</a:mn><a:mn>6</a:mn></a:msup></a:math> events in the rigidity range from 1.00 to 41.9 GV. The <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mover accent="true"><c:mi>p</c:mi><c:mo stretchy="false">¯</c:mo></c:mover></c:math> fluxes exhibit distinct properties. magnitude...
We analyze the timing of photons observed by MAGIC telescope during a flare active galactic nucleus Mkn 501 for possible correlation with energy, as suggested some models quantum gravity (QG), which predict vacuum refractive index ≃1+(E/MQGn)n, n=1,2. Parametrizing delay between γ-rays different energies Δt=±τlE or Δt=±τqE2, we find τl=(0.030±0.012) s/GeV at 2.5-σ level, and τq=(3.71±2.57)×10−6 s/GeV2, respectively. use these results to establish lower limits MQG1>0.21×1018 GeV...
We report on the results from observations in very high energy band (VHE; Eγ ≥ 100 GeV) of black hole X-ray binary (BHXB) Cygnus X-1. The were performed with MAGIC telescope, for a total 40 hr during 26 nights, spanning period between 2006 June and November. Searches steady γ-ray signals yielded no positive result, upper limits to integral flux ranging 1% 2% Crab Nebula flux, depending energy, have been established. also analyzed each observation night independently, obtaining evidence at...
We have performed a detailed oxygen abundance analysis of 23 metal-poor (-3.0 < [Fe/H] -0.3) unevolved halo stars and one giant through the OH bands in near UV, using high-resolution echelle spectra. Oxygen is found to be overabundant with respect iron these stars, [O/Fe] ratio increasing from 0.6 1 between = -1.5 -3.0. The behavior overabundance similar that seen previous works based on O I IR triplet data. Contrary previously accepted picture, our abundances, derived low-excitation lines,...
We have observed the spectrum of Procyon A (F5 IV) from 4559 to 5780 Å with a signal-to-noise ratio ~103 and resolving power 2 × 105. measured line bisectors relative shifts large number Fe I II lines, comparing them those found in solar spectrum. three-dimensional hydrodynamical model atmosphere has been computed is tested against observations. The reproduces detail most features observed, although we identify some room for improvement. At all levels, comparison time-dependent calculations...